Generation of electrical signals corresponding to musical tones in electronic organs and other musical instruments has been effected in the past by many different structures. Electro-mechanical devices have been used, such as windblown, vibrating reeds, rotating tone wheels with magnetic or photoelectric transducers, or actual recordings of conventional musical instruments. Probably the most prevalent practice in recent years has been the provision of 12 discrete oscillators to generate the semitones of the top octave of the instrument (or harmonics thereof), each driving a divide-by-two divider train to produce the corresponding frequencies of lower octaves of the instrument. This has required individual tuning of the 12 discrete master oscillators, but of course has avoided tuning of the corresponding notes of lower octaves.
With the advent of large scale integrated circuits it has been possible to provide a single radio frequency oscillator with a plurality of parallel divider paths of different divider ratio to produce the 12 frequencies of the top octave of the instrument, followed by the known divide-by-two circuits to produce the corresponding frequencies of lower octaves. This has reduced the tuning requirements during manufacture to a single oscillator. Such a generating system is suggested in Freeman U.S. Pat. No. 3,236,931, and is clearly taught in Reyers U.S. Pat. No. 3,590,131. This structure has proved commercially acceptable. However, these circuits have division ratios and waveform symmetry properties that are difficult and/or costly to modify.